Various types of chemical lasers are known. These comprise two main types:
a. The first type is based on in situ mixing of an oxidizer and a fuel gas, producing a continiuous output. The gas mixture can be activated by means of electrical discharge (microwave, RF or DC), or by thermal decomposition (archeaters or combustors), to produce reaction-initiating species. The rate of the chemical reaction is diffusion dominated and thus this type of laser must be operated at comparatively low pressures (of the order of 1-20 Torr), so that the rate of production of lasing species will exceed the rate of their collisional deactivation. PA1 b. The second type is based on the use of premixed fuels and oxidizers, where the necessary reaction-initiating species are produced by flash photolysis, by an electron beam, or by a pulsed discharge. Such premixed reactants may present flameout and detonation problems. Once the mixture is ignited, it is difficult to extinguish it, and the combustion is apt to transform via a chain reaction into a detonation wave which can cause damage to the device.
Two main types of molecules are operated as lasing species in chemical lasers: hydrogen halide (HX) and carbon monoxide (CO). For HX lasers suitable fuels are hydrogen (or deuterium) containing molecules such as hydrogen, hydrocarbons, and various organic and inorganic hydrides; suitable oxidizers are halogen containing molecules such as fluorine, nitrogen tri-fluoride, sulfur hexafluoride, chlorine, bromine, and various organic and inorganic halides. In order to inhibit prereaction in fuel-oxidizer mixtures suitable radical scavengers such as oxygen and nitrous oxide can be used. For CO lasers suitable fuels are carbon containing molecules such as carbon disulphide and carbon diselenide; suitable oxidizers are oxygen containing molecules such as oxygen, ozone, nitrous oxide, and sulfur dioxide. The active reactants are often diluted with a suitable inert gas such as helium, arson, and nitrogen. Detailed lists of fuel, oxidizers, and diluents for chemical lasers are given in "Handbook of Chemical Lasers", edited by R. W. F. Gross and J. F. Bott (Wiley, N.Y., 1976), and these are suitable for use in a system of the type disclosed herein.